Fetal nucleic acids in maternal plasma.

The discovery of cell-free fetal nucleic acids in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis. Over the last few years, a number of approaches have been demonstrated to allow such circulating fetal nucleic acids to be used for the prenatal detection of chromosomal aneuploidies. One such approach involves the enrichment of fetal DNA, such as by size fractionation or by the controversial formaldehyde treatment technique. A second approach involves the targeting of fetal-specific nucleic acid molecules, including fetal-specific epigenetic markers and placenta-specific mRNA markers. A third approach involves the development of highly discriminatory quantitative methods for chromosome dosage analysis using digital polymerase chain reaction technology. It is likely that these and other methods yet to be developed would allow noninvasive prenatal diagnosis of chromosomal aneuploidies by maternal plasma nucleic acids to be realized in the near future.